When Saladin took over Egypt in the 1170s, he decided to build a new palace for his new dynasty in the hills of Cairo. A bit surprisingly many of the skilled workers who created his palace were captive crusaders. The Europeans utilized techniques unknown to the Middle East at the time, which is rather helpful in determining who built the palace.
Crusader architecture was stronger and lasted longer. It also enabled building larger buildings. Over time, Muslims in the Middle East learned these new (to them) techniques, often by studying castles built by crusaders across the eastern Mediterranean seaboard.
